Charge distribution studies in the epi-cadmium neutron induced fission of 235U

For the first time, charge distribution studies have been carried out in the epi-cadmium neutron induced fission of 235U by measuring the fractional cumulative yields (FCY) and independent yields (IY) of various fission products. An off-line γ-ray spectrometric technique was used for the measurements. The average energy of the epi-cadmium neutron spectrum is 1.9 MeV. From the FCY values, the isobaric width parameter (σZ), most probable charge (ZP) and the charge polarization (ΔΖEXPT) as a function of fragment mass were obtained. Similarly, from the IY values, isotopic width parameter (σA), the most probable mass (AP) and the elemental yields (YZ) of Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce and Pr were determined by using a non-linear fit. From the YZ values, the proton even-odd effect (δp) was obtained for the first time. The present data in the 235U(n, f) reaction were compared with the similar data in the 235U(nth, f) and 238U(n, f) reactions as well as of other actinides to examine the role of excitation energy and pairing effect.

Charge distribution studies in the epi-cadmium neutron induced fission of 238Pu

Studies on charge distribution have been carried out in the epi-cadmium neutron induced fission of 238Pu for the first time. Experimentally fractional cumulative yields (FCY) and independent yields (IY) of various fission products have been measured by using an off-line γ-ray spectrometric technique. From the FCY values, the charge distribution parameters such as the isobaric width parameter (σZ), most probable charge (ZP) and the charge polarization (ΔΖEXPT) as a function of fragment mass were obtained. On the other hand, from the measured IY values, isotopic width parameter (σA), the most probable mass (AP) and the elemental yields (YZ) of Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce and Pr were determined by using a non-linear fit. From the YZ values, the proton even-odd effect (δp) was obtained for the first time. The isobaric and isotopic charge distribution parameters in the 238Pu(nf, f) reaction were compared with the similar data in the thermal neutron induced fission of 238Pu and other actinides to examine the role of excitation energy.

Charge distribution of light mass fission products in the thermal neutron induced fission of 233U, 235U and 239Pu

Fractional cumulative yields (FCY) of various light mass fission products in the ²³³U(n_th, f), ²³⁵U(n_th, f) and ²³⁹Pu(n_th, f) reactions were measured by using an off-line γ-ray spectrometric technique. The values of most probable charge (Z_P) were obtained by using the width of isobaric charge distribution (σ_Z) of nearby fissioning systems with proper apportion. From the Z_P values, the experimental charge polarization (ΔΖ_EXPT) as a function of fragment mass were also deduced. The ΔΖ_EXPT values for the light mass chains from the present work and for the heavy mass chains from earlier work show an oscillating nature in the interval of five mass units due to even-odd staggering. A local effect around the shell region and a systematic decreasing trend with the approach of symmetric split was also observed. The ΔΖ_MPE values based on minimum potential energy surface were theoretically calculated, which shows no oscillation but only a systematic decreasing trend with the approach of symmetric split due to the assumption of liquid drop behaviour of the fissioning nucleus.